Power tool torque indicating device

ABSTRACT

A pneumatic power tool drive mechanism having coaxial drive and driven rotors and an intermediate torsion spring and relatively rotatable in accordance with the transmitted torque. A torque indicating device of the power tool comprises an axially reciprocable and non-rotatable torque scale operator actuated in one axial direction in accordance with the relative angular displacement of the drive and driven rotors to indicate the applied torque and urged in the opposite axial direction to reset the torque scale operator through the engagement of dimples on the torque scale operator with a helical cam on the driven rotor.

United States Patent 1191 1111 3,844,169 Whitehouse Oct. 29, 1974 [54] POWER TOOL TORQUE INDICATING 3,666.021 5/1972 Whitehouse 73/139 x DEVICE Primary Examiner-Charles A. Ruehl I ['75] mentor L whitehouse Lyndhurst Attorney, Agent, or Firm-Prutzman, Hayes, Kalb &

Chilton 7 [73] Assignee: The Stanley Works, New Britain,

[57 ABSTRACT Filedi p 13, 1973 A pneumatic power tool drive mechanism having co- [21] APPL N0: 352,109 axial drive and driven rotors and an intermediate tors1on sprlng and relat1vely rotatable 1n accordance w1th the transmitted torque. A torque indicating device of [52] US. Cl. 73/136 A, 73/139 the power tool comprises an axially recip ocable and ll'lt. Cl. G011 nonqotatable torque cale operator actuated in one Fleld 0f sealclh- 136 136 B, 136 axial direction in accordance with the relative angular BILQAS E displacement of the drive and driven rotors to indicate the applied torque and urged in the opposite axial di- References Cited rection to reset the torque scale operator through the UNITED STATES PATENTS engagement of dimples on the torque scale operator 3,084,540 4/1963 Larkin 73/136 A with a helical cam the drive" 3,l04,544 9/l963 Guiot 73/136 A 3,339,405 9/1967 McDowall 73/136 A 9 Chums 3 Draw; guns 1'? M 1 R f 4 47" 44 m 41 X, V, 1,5, IIG;.I,I;I;-I .Y,7 g .l HI; 2 '2, 1

POWER TOOL TORQUE INDICATING DEVICE BRIEF SUMMARY OF THE INVENTION The present invention relates generally to power tools for example of the type shown in my US. Pat. No. 3,666,021 dated May 30, 1972 and entitled Power Tool Having Proportioning Transmission and relates particularly to a new and improved power tool torque indicating device for indicating the applied torque of the power tool.

It is a principal aim of the present invention to provide a new and improved torque indicating device for a power tool for automatically indicating the applied torque of the power toolduring the operation of the power tool.

It is another aim of the present invention to provide a new and improved torque indicating device for a power tool for setting fasteners or the like which registers the peak applied torque of a power tool operation and which is automatically reset to register the applied torque of a subsequent power tool operation.

It is a further aim of the present invention to provide a new and improved power tool torque indicating device capable of accurately and continuously indicating the torque being applied by the power tool during the operation of the tool and for indicating the peak applied torque after the power tool is deactivated.

Other objects will be in part obvious and in part pointed out in more detail hereinafter.

A better understanding of the invention will be ob- ,tained from the following detailed description and the accompanying drawingof an illustrative application of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a partial longitudinal view, partly in section and partly broken away, of a pneumatic power tool incorporating an embodiment of a torque indicating device of the present invention,

FIG. 2 is a transverse section view, partly broken away and partly in section, of the power tool taken substantially along line 2-2 of FIG. I; and

FIG. 3 is a partial longitudinal view, partly broken away, of the power tool showing an indicator of the torque indicating device.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in detail, there is shown in part a pneumatically driven power tool 10 of the type shown in the aforementioned US. Pat. No. 3,666,021. The power tool 10 is shown comprising an elongated housing 12 having a drive mechanism with a rotary drive rotor l4rotatably mounted within the housing 12 and driven by a suitable air motor (not shown) in the counterclockwise direction as viewed in FIG. 2, a rotary driven motor 16 rotatably mounted within the housing 12 coaxially with the drive rotor 14 and an intermediate generally helical torsion spring 18 interconnecting the rotary drive'and driven rotors l4, 16.

The helical torsion spring 18 provides for transmitting the drive torque from the drive rotor 14 to the driven rotor 16, and for this purpose the radially inturned ends 19, 20 of the torsion spring 18 are received within slots in the bifurcated inner ends 21, 22 of the rotors l4, 16 respectively. It can be seen therefore that the drive and driven rotors rotate generally together and that any angular displacement of the drive rotor 14 relative to the driven rotor 16 loads the torsion spring 18 and is directly proportional to the torque being transmitted through the drive mechanism. The drive torque is in turn a function of the rotational resistance or drag on the driven rotor 16. Also, as fully explained in my US. Pat. No. 3,666,021, the static drive torque applied through the drive mechanism is a function of the static drive torque of the driving air motor (not shown); and the peak torque applied as the power tool is stalled, for example accompanying setting a fastener, may exceed the static drive torque due to an additional torque increment caused primarily by the inertia of the drive motor (not shown) of the power tool as the power tool is decelerated to a stall.

The drive and driven rotors l4, 16 have coaxial telescoping or interfitting tubular sleeves 28, respectively. The driven rotor sleeve 30 is mounted upon axially spaced flanges 31, 32 of a spool portion of the driven rotor 16 and is secured for rotation therewith by a set screw operated wedge 33. The drive rotor sleeve 28 has an inner hub 35 mounted on the splined end of a drive shaft 36 of the drive rotor 14, and the bifurcated inner end 22 of the drive rotor 14 is keyed to the hub 35 of the sleeve 28 by pins 38 such that the sleeve 28, shaft 36 and bifurcated end 22 rotate together. Also, as

7 can be seen in the drawing, the driven rotor sleeve 30 extends substantially to the opposite end of the drive rotor sleeve 28 such that the sleeves, though relatively rotatable, provide mutual support.

An'actuating slide or collar 40 is mounted on the driven rotor sleeve 30 for rotation with the sleeve 30 and for axial movement along the sleeve 30. A follower 42 is mounted on the inside of the collar 40 for receipt within an axial slot 44 in the driven rotor sleeve 30 and operator is mounted on the outer sleeve 30 to be actuated in one axial direction, to the right as shown in FIG. 1, by the collar 40. The circumferential ends of the C-shaped indicator slide 50 are formed to provide outtumed edges or lips 54, and a screw 56 is mounted on the housing 12 to extend into the slot 57 formed between the edges 54 to prevent rotation of the indicator slide 50 while permitting the indicator slide 50 to move axially back and forth within the housing 12. A torque scale 58, which for example may be a suitable decal, is mounted on the indicator slide 50 in alignment with a window 60 in the housing 12 and such that the scale may be readily read with a cross hair 64 of the window 60. The torque scale 58 is preferably calibrated to give a direct reading of the applied torque (e.g.', in ft., lbs.) at the output end (not shown) of the pneumatic power tool.

It can be seen that as the indicator slide 50 is actuated in only one axial direction by the collar 40, to the right as seen in FIG. 1, the torque scale will provide a reading of the peak applied torque as for example when the power tool is stalled when setting fasteners. Typiteners, the power tool is thereafter deactivated (by closing a valve, not shown, to disconnect the air pressure source from the pneumatic drive motor) while it is still connected to the fastener and such that the torsion spring is unwound or unloaded by rotating the drive rotor 16 backwards, in the clockwise direction as viewed in FIG. 2, until the torsion spring returns to its normal orunloaded condition. The power tool is then removed from the fastener. As a result, the collar 40 returns to its normal position shown in FIG. 1, and the torque scale operator 50 remains in its displaced position, for example as shown in H6. 1, so that the torque scale continues to registerthe peak applied torque of the prior power tool operation, for example as shown in FIG. 3. V 4

The driven rotor sleeve 30 is formed with an external helical land or thread 70 having tapered lateral edges 72 and defining an intermediate helical groove 74. The indicator slide 50 is formed with a pair of cooperating generally radially inwardly projecting dimples 80 which are adapted to ride within the groove 74, and for this purpose the indicator slide 50 is formed to grip the helical land 70 lightly like a leaf spring. The helical land 70 functions as a helical cam and the dimples 80 function as cam followers engageable with the helical cam to urge the indicator slide 50 to the left as shown in FIG. 1 to return the indicator slide 50 to its zero or normal position. The dimples 80 are preferably provided relatively close to the circumferential'ends of the slide 50 and such that the circumferential ends of the slide 50- can flex outwardly slightly to permit the dimples 80 to ride over the land 70. Accordingly, the indicator slide 50 can be positively actuated to the right as seen in FIG. 1 by the collar 40 notwithstanding any opposing bias on the slide 50 by the cam 70. The land '70 preferably extends axially only as far as is necessary to return the indicator slide 50 to its normal or zero position and such that the dimples 80 remain out of engagement with the land 70 with the indicator operator 50 in its zero position.

Accordingly, the dimples 80 and helical cam 70 cooperate to urge the indicator slide 50 to the left as seen in F IG. 1 while the driven rotor 16 is rotating and at any time the indicator operator is axially displaced from its zero position. Thus, the torque scale 58 will continuously provide for registering the existing applied torque as long as the driven rotor 16 is rotating. When tool stall occurs the return bias provided by the cam 70 and dimples 80 is deactivated and the indicator slide 50 will be effective in indicating any peak applied torque accompanying power tool stall. Thus, as previously described wherefor example the power tool is used for setting fasteners and the power tool is deactivated before it is removed from the fastener, the torque scale will continue to register the peak applied torque of the prior power tool operation. When the power tool is subsequently reactivated, the indicator slide 50 is auto matically reset into engagement with the collar 40 to return the indicator slide 50 to zero or to register the then existing applied torque, as the case may be.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

I claim:

1. ln apower tool having a rotary drive mechanism with generally coaxial rotary drive and driven members and intermediate torque transmitting means interconnecting the rotary drive and driven members and permitting relative angular displacement thereof in accordance with the torque being transmitted therethrough, a torque indicating device comprising torque indicating means operable for indicating torque, a torque indicatoroperator for operating the indicating means, the torque indicator operator being reciprocably mounted in association with the drive mechanism for movement in one direction for increasing the torque indication and for movement in the opposite direction for decreasing the torque indication, first actuator means for actuating the torque indicator operator in said one direction in accordance with said relative angular displacement of the rotary drive and driven members for indicating the torque transmitted through the drive mechanism, and second actuator means operable by the rotation of one of the rotary members for actuating the torque indicator operator in the opposite direction when the indicated torque is greater than the transmitted torque.

2. A power tool according toclaim 1 wherein the rotary drive and driven members respectively comprise coaxial portions in telescoped relation, and wherein the first actuator means comprises an axially reciprocable slide for actuating the indicator operator in said one direction, and means for axially shifting the slide back and forth in accordance with the relative angular displacementof the rotary drive and driven members.

3. A power tool according to claim 1 wherein the torque indicator operator is mounted for movement generally parallel to the axis of rotation of the rotary drive and driven members and wherein the second actuator means comprises cam means and follower means interconnecting the indicator operator and said one rotary member and operable to urge the indicator operator in its said opposite direction upon said rotation of said one rotary member.

4. A power tool according to claim 3 wherein said one rotary member has said cam means and the indicator operator has said follower means.

'5. A power tool according to claim 4 wherein the indicator operator has at least one projection providing said follower means and engageable by the cam means of said one rotary member to urge the indicator operator in its said opposite direction.

6. A power tool according to claim 4 wherein the indicator operator comprises a generally C-shaped member partially surrounding said one rotary member and the follower means is provided adjacent at least one circumferential end of the C-shaped member.

7.A power tool according to claim 1 wherein said one rotary member is the driven rotary member.

8. in a power tool having an elongated housing with an indicator window therein, a rotary drive mechanism mounted within the housing having longitudinally spaced generally coaxial rotary drive and driven members and intermediate torque transmitting means comprising spring means interconnecting the rotary drive and driven members, a torque indicating device comprising a torque indicator mounted for axial reciprocable movement within the housing in operative alignment with the indicator window, actuator means for shifting the torque indicator in one axial direction in proportion to the relative angular displacement of the LII dicator return means is operable by the rotation of said one rotary member for biasing the torque indicator in said opposite axial direction and wherein said actuator means is operable to shift the torque indicator in said one axial direction against the bias of the indicator return means. 

1. In a power tool having a rotary drive mechanism with generally coaxial rotary drive and driven members and intermediate torque transmitting means interconnecting the rotary drive and driven members and permitting relative angular displacement thereof in accordance with the torque being transmitted therethrough, a torque indicating device comprising torque indicating means operable for indicating torque, a torque indicator operator for operating the indicating means, the torque indicator operator being reciprocably mounted in association with the drive mechanism for movement in one direction for increasing the torque indication and for movement in the opposite direction for decreAsing the torque indication, first actuator means for actuating the torque indicator operator in said one direction in accordance with said relative angular displacement of the rotary drive and driven members for indicating the torque transmitted through the drive mechanism, and second actuator means operable by the rotation of one of the rotary members for actuating the torque indicator operator in the opposite direction when the indicated torque is greater than the transmitted torque.
 2. A power tool according to claim 1 wherein the rotary drive and driven members respectively comprise coaxial portions in telescoped relation, and wherein the first actuator means comprises an axially reciprocable slide for actuating the indicator operator in said one direction, and means for axially shifting the slide back and forth in accordance with the relative angular displacement of the rotary drive and driven members.
 3. A power tool according to claim 1 wherein the torque indicator operator is mounted for movement generally parallel to the axis of rotation of the rotary drive and driven members and wherein the second actuator means comprises cam means and follower means interconnecting the indicator operator and said one rotary member and operable to urge the indicator operator in its said opposite direction upon said rotation of said one rotary member.
 4. A power tool according to claim 3 wherein said one rotary member has said cam means and the indicator operator has said follower means.
 5. A power tool according to claim 4 wherein the indicator operator has at least one projection providing said follower means and engageable by the cam means of said one rotary member to urge the indicator operator in its said opposite direction.
 6. A power tool according to claim 4 wherein the indicator operator comprises a generally C-shaped member partially surrounding said one rotary member and the follower means is provided adjacent at least one circumferential end of the C-shaped member. 7.A power tool according to claim 1 wherein said one rotary member is the driven rotary member.
 8. In a power tool having an elongated housing with an indicator window therein, a rotary drive mechanism mounted within the housing having longitudinally spaced generally coaxial rotary drive and driven members and intermediate torque transmitting means comprising spring means interconnecting the rotary drive and driven members, a torque indicating device comprising a torque indicator mounted for axial reciprocable movement within the housing in operative alignment with the indicator window, actuator means for shifting the torque indicator in one axial direction in proportion to the relative angular displacement of the drive and driven members for indicating the torque being transmitted through the drive mechanism, and torque indicator return means interconnecting the torque indicator and one of the rotary members and operable by the rotation of said one rotary member for shifting the torque indicator in the opposite axial direction.
 9. A power tool according to claim 8 wherein the indicator return means is operable by the rotation of said one rotary member for biasing the torque indicator in said opposite axial direction and wherein said actuator means is operable to shift the torque indicator in said one axial direction against the bias of the indicator return means. 